Electric discharge machining method and device

摘要

PCT No. PCT/JP87/00868 Sec. 371 Date Aug. 25, 1988 Sec. 102(e) Date Aug. 25, 1988 PCT Filed Nov. 10, 1987 PCT Pub. No. WO88/03453 PCT Pub. Date May 19, 1988.An electric discharge machining device, in which a pulse voltage is repeatedly applied between electrodes, which are an electrode and a workpiece to be machined, to cause electric discharge between the electrodes and thereby machine the workpiece. The electric discharge machining device includes a switching device (4) connected between a power source and the machining section, for controlling energy supplied by the power source; interelectrode impedance detecting apparatus (10) for detecting an interelectrode impedance affected by the variation in place of electric discharge which takes place between the electrodes; discharge detecting apparatus for detecting when electric discharge takes place between the electrodes; and a control device (18). The control device utilizes the output of the interelectrode impedance detecting apparatus to calculate a power source internal impedance to obtain a desired no-load voltage, and a power source internal impedance to obtain a desired current at the detection of electric discharge to thereby control the switching device. As a result, the discharge machining operation is stably carried out, the machined surface is uniform in surface roughness, and for a desired surface roughness the highest machining speed can be employed.